Sun in the 6th house (Ari / Shatru, the house of health & service) brings the significations of Sun, namely soul (atma), father, authority & government, into the area of health, service, competition and the obstacles you overcome. The 6th house governs enemies & competition, disease & health, debts, daily work & service.
Results of Sun in the 6th House
Sun is a malefic planet, so here it tends to bring low confidence, ego conflicts, trouble with father or bosses, and weak vitality focused on health, service, competition and the obstacles you overcome. As the 6th is a dusthana (difficult) house, results may come through struggle before growth.The exact result depends on which sign Sun occupies here and the aspects it receives.
When It Activates
These results typically surface during the Vimshottari mahadasha or antardasha of Sun, and when transiting planets trigger the 6th house. A well-placed Sun here supports the power to defeat enemies, good health with effort and success in service; when afflicted it can indicate chronic illness, mounting debts and strong opposition from rivals.